Dunnage bags are large bags for inflation with air so as to provide pressure against cargo during transportation to prevent movement of the cargo. The bags are provided in different dimensions for different situations. The bags can be manufactured from a number of paper plies with an inner air impervious liner or from a lined fabric as is well known to one skilled in the art. The paper products are generally manufactured for one time use and are deflated simply by slashing open the bag to release the air quickly and allow the bag to be pulled from its location to release the cargo for unloading.
It is proposed that bags manufactured from lined fabric can be reused on a number of occasions and thus require a valve which allows deflation of the bag rapidly but without slashing an opening in the bag.
In addition the use of a valve which rapidly allows deflation of the bag also provides the opportunity for inflating the bag prior to use to test its air tightness. One serious problem with the single use paper bags is that they are untested and thus have a relatively high failure rate which can be as much as thirty percent. If the bag fails during transport, the load may become loose and can shift with potential for significant damage. If the bag fails during loading, it is of course inconvenient to remove the failed bag and to replace it with a further bag. The pre-testing of the bags is therefore highly desirable and provides a significant sales advantage.
Valves used simply for rapid inflation require simply a valve stem with an inflation head which can be attached onto the stem to allow the user to inflate the bag. In many cases the inflation head or nozzle has a system for attachment to the valve stem so that it remains in place during the inflation without necessity for the user to hold it in place.
Examples of a valve and inflation device of this type are shown in U.S. Pat. No. 5,839,488 (Peters) and U.S. Pat. No. 5,082,244 (Krier). The arrangement of Krier requires pushing of the nozzle onto the valve stem, which may be difficult if the portion of the bag where the valve is located has nothing suitable behind it against which to receive the pushing forces.
Another example of a valve of this type which uses a bayonet type fitting is shown in U.S. Pat. No. 5,111,838 (Langston). In this arrangement also it is necessary to push the inflation head onto the valve in order to depress the valve member against its spring bias.
These arrangements are therefore not properly designed in order to allow the user to readily fit the inflation head onto the valve.
Also the above designs are arranged simply for inflation of the bag with the intention that the bag will be slit open. This arrangement does not therefore allow a pre-testing of the bag or a reuse of the bag since the bag can not be rapidly deflated.
In U.S. Pat. No. 5,275,197 (Finell) is disclosed an arrangement in which the bag can be rapidly deflated by removing or loosening a cap on a relatively wide valve stem so that the air can rapidly escape through the valve stem and through holes provided in the cap. In this arrangement the valve itself is mounted in the cap and comprises a simple split tube which is located at the centre of the cap. Filling is effected by an injection nozzle which is inserted through the tube and opens the split part of the tube to allow the air to enter. When the nozzle is removed the two split parts are compressed together by the air pressure thus preventing air release. However this type of valve is very crude and can lose air. Also the user has to push the nozzle or tip into the valve thus requiring a significant pushing force against the valve.